U.S. FDA warns about false positive results from COVID-19 antigen tests

(Reuters) – The U.S. Food and Drug Administration said on Tuesday it is alerting clinical laboratory staff and healthcare providers that false positive results can occur with COVID-19 antigen tests.

The decision was made following reports of false positive results associated with the tests used in nursing homes. [bit.ly/389ohyw]

The U.S. agency said false positive results may occur when users do not follow the instructions for the use of antigen tests for rapid detection of SARS-CoV-2.

FILE PHOTO: Signage is seen outside of the Food and Drug Administration (FDA) headquarters in White Oak, Maryland, U.S., August 29, 2020. REUTERS/Andrew Kelly

Antigen tests detect proteins on the surface of the virus. They require an uncomfortable nasal or throat swab, and can produce results more quickly than molecular tests – which detect genetic material in the virus – but are considered less accurate.

Countries straining to contain a second wave of COVID-19 are turning to faster, cheaper but less accurate tests to avoid the delays and shortages that have plagued efforts to diagnose and trace those infected quickly.

The FDA issued the first emergency use authorization (EUA) for a COVID-19 antigen test in May.

The U.S. government has signed agreements with several companies including Becton Dickinson BDX.N and Quidel Corp QDEL.O to supply antigen tests to U.S. nursing homes in an attempt to identify outbreaks faster and stem the tide of the virus.

In September, Becton Dickinson, which is supplying 750,000 of its SARS-CoV-2 antigen test to the U.S. government, said it is investigating reports from U.S. nursing homes that its rapid coronavirus testing equipment is producing false-positive results.


Reporting by Mrinalika Roy in Bengaluru; Editing by Maju Samuel


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